1. Field of the Invention
The present invention relates to an image blur correction apparatus for preventing an image blur caused by a hand shake or the like in cameras, optical equipment, and so on.
2. Related Background Art
There are a variety of conventional devices for image blur correction of camera and some types of conventional blur correction methods. Among the image blur correction methods used in cameras etc., a typical example is a method for driving a part or the whole of a photographing optical system, based on information about the shake of camera detected by a fluctuation detecting sensor, so as to prevent the image blur on the image plane.
The image blur correction apparatus of this type is normally arranged to suitably prevent vibration due to the hand shake or vibration having a frequency distribution similar thereto; specifically, the fluctuation detecting sensor and a driving mechanism for a blur correction optical system are selected so as to be compatible with the vibration and a response frequency band of the fluctuation detecting sensor and driving mechanism is set according thereto.
The image blur correction apparatus of this type thus has the following problems when panning, which is an operation of camera, is carried out or when photography with a tripod is done under the above setup.
During the panning the apparatus operates to compensate for the operation of panning in the same manner as in the case of the vibration, thereby working against the panning.
During the operation with the tripod the vibration due to the hand shake is very little, while mounting of the tripod becomes a cause of image blur because of vibration from the ground, though little, and because of high-frequency impact from a quick return mirror or a shutter mechanism. These vibrations could be a cause of output of an error signal from the fluctuation detecting sensor, and actuation of the blur preventing mechanism during the operation with the tripod will sometimes cause the image blur to the contrary. If the image blur correction mechanism is also actuated under the circumstances not necessitating prevention of blur, there will arise a problem that the power is dissipated more than necessary.
In view of this aspect, for example, Japanese Patent Application Laid-Open No. 5-134283, which was filed by the present applicant, proposed a camera permitting selection of a blur prevention mode by means of switch means for selection thereof out of a normal prevention mode having an image blur correction characteristic with more emphasis on the normal prevention of hand shake, a blur prevention mode having an image blur correction characteristic with more emphasis on a panning countermeasure (a blur prevention mode for panning), and a blur prevention mode having an image blur correction characteristic with more emphasis on a tripod countermeasure (a blur prevention mode for tripod).
With the camera having the plural blur prevention modes, there would occur improper selection of a blur prevention mode selected by the operation of the camera.
For example, when during selection of the prevention mode for tripod or the prevention mode for panning the power supply of the camera was turned off once and then again on and if the camera was of a type maintaining a previous prevention mode as it was, there occurred some troubles where a beginner carried out photography in the expectation of the normal prevention mode without being aware of that fact, resulting in failure in photography because of the mischoice of the prevention mode.
On the other hand, the apparatus can also be constructed to set a non-prevention mode or the blur prevention mode having the image blur correction characteristic with more emphasis on the normal hand shake prevention on the occasion of next power-on, but, for example in the case of a man intending to continue photography with the tripod, if the prevention mode is changed as described above every off of power, the man has to change the blur prevention mode to the prevention mode for tripod every next power-on, resulting in poor operability.